Is Cycle Time different between Parallel Machines and Single?

[charliekh]

I am very confused that the cycle time when mapping VSM, does the cycle time is the same between parallel machines and single machine? for example, rough tunning for forging is 60s in one machine and for one piece, the cycle time is 60s, but now there are 10 rough turnning machines paralle turnning 10 forgings, the throughput is 10pcs in 60s, does it mean the cycle time is 6s? the cycle time definition in VSM is the time between two finished products. could anyone explain it to me, thanks very much!

 

[Jen Kirley]

Good day,

In business management we are often asked for overall process measurements. For the purposes of reporting to management it's realistic to provide an average performance metric among all tools of the same type, but we must understand the purpose of the metric. The purpose is to form a comparison between the present and what we strive to achieve.

While the cycle time metric is often expressed as a process measurement of "time end minus time begin," it may prove useful to take this measurement at each tool if one suspects tools may vary in performance. How else could we identify where, when, how and why the problem is occurring?

In short, measure at the local (immediate) level and report at the macro (overall) level.

I hope this helps!

 

[somashekar]

I am very confused that the cycle time when mapping VSM, does the cycle time is the same between parallel machines and single machine? for example, rough tunning for forging is 60s in one machine and for one piece, the cycle time is 60s, but now there are 10 rough turnning machines paralle turnning 10 forgings, the throughput is 10pcs in 60s, does it mean the cycle time is 6s? the cycle time definition in VSM is the time between two finished products. could anyone explain it to me, thanks very much!

The cycle time best fits for an article in a defined process. How you handle a batch production of that article depends upon your resources and quantity required to be produced. Perhaps that becomes the throughput time for that batch.

 

[charliekh]

Still can not know the exact answer.Can anyone let me know clearly how to fill the cycle time when meet these two situation? Is the same cycle time regardless how many machines or operators do the same operation?

 

[Pudge 72]

The answer is yes.
Cycle time will not change unless you improve the process whether you have 1machine or 20.

Throughput would be the metric associated with additional equipment.

 

[Jen Kirley]

Still can not know the exact answer.Can anyone let me know clearly how to fill the cycle time when meet these two situation? Is the same cycle time regardless how many machines or operators do the same operation?

It is easy to confuse process cycle time with machine cycle time. Both can be measured, but both are done separately.

We measure individual machine time to understand the machine's process time. This enables us to make and understand improvements that are specific to the machine. This is reported to lower levels so best practices can be applied to other machines. It is a result measurement. It is a micro measurement of tasks and strategy.

The machines (all together) contribute to a process cycle time that is reported to management in whatever defined form. This is a measure of total outcomes in the process. It is a macro measurement, a means to communicate overall program success against objectives.

I hope this helps!

 

[George Weiss]

The question is what do I enter into the VSM data entry point of my program right?
I have a web link to such a process. @
http://www.gemba.com/uploadedFiles/Lean%20VSM%20Diagrams%20Quick%20Reference%20Guide.pdf
It indicates the need to enter C/T and C/O times, which are per person/per machine
C/T cycle time part to part
C/O change over to another process time
The value is an average value if you have 10 people/machines doing 10 parts as described on an earlier post.
(This means you could time each machine seperately and get the average time for 1 part. 60 seconds)
This all leads back to your question, of what do I enter into the VSM system.
You should enter the time each part takes to be made.
Then enter the number of machines/people to get a process throughput somewhere else in the data entry form.
So enter 60 sec. For C/T time. The VSM program is likely to ask how many people/machines at this step.
The time does not change for 1 or 1000 machines in this/your VSM analysis program. (maybe +/- 2 seconds)
The above comments were all valid, but did not quite respond to your specific question of what do I enter into the C/T entry box.
==== If you are not using the VSM program as I thought, then C/T is still defined as single part time in the VSM process =========
looking for comment...........................

 

[charliekh]

The question is what do I enter into the VSM data entry point of my program right?
I have a web link to such a process. @
http://www.gemba.com/uploadedFiles/Lean%20VSM%20Diagrams%20Quick%20Reference%20Guide.pdf
It indicates the need to enter C/T and C/O times, which are per person/per machine
C/T cycle time part to part
C/O change over to another process time
The value is an average value if you have 10 people/machines doing 10 parts as described on an earlier post.
(This means you could time each machine seperately and get the average time for 1 part. 60 seconds)
This all leads back to your question, of what do I enter into the VSM system.
You should enter the time each part takes to be made.
Then enter the number of machines/people to get a process throughput somewhere else in the data entry form.
So enter 60 sec. For C/T time. The VSM program is likely to ask how many people/machines at this step.
The time does not change for 1 or 1000 machines in this/your VSM analysis program. (maybe +/- 2 seconds)
The above comments were all valid, but did not quite respond to your specific question of what do I enter into the C/T entry box.
==== If you are not using the VSM program as I thought, then C/T is still defined as single part time in the VSM process =========
looking for comment...........................

Hi george1weiss,
Many thanks for your deteailed explanation!

 

[laecengineer]

Hi george1weiss,
Many thanks for your deteailed explanation!

In an expansion to the previous discussions, I find myself having difficulty using a VSM to describe a production process which contains several automated machines which operate in series/parallel with each other and in series with a combined manual / automated operation in a cell utilizing a single operator.

Each of automated machines have unequal processinging times

mach 1 - 1 min,
mach 2 -5 min,
mach 3 -1 min

Each machine 1-3 includes a 1 unit buffer to hold a completed unit available to the operator for processing.

Once each of the buffers are full, the operator, using the unit in mach 3 buffer, initiates the manual/ automated process of mach 4 which takes several steps and contains several periods of wait time during which the operator moves material through the mach 3, mach 2, mach 1 cycles, utilizing, in this sense, SMED principles to allow the processing times of mach 1-3 to be aborbed by the time required for the operations of mach 4

Use of the VSM to show cycle time, total cycle time, process time, for this cell and yet be fully descriptive of each machine is where I have difficulty, except if I show the cell as having all of the machines in parallel with each other and report the cell cycle time in addition. Any comments anyone?

 

[IEsaif]

Hi!
I've done my thesis on VSM and first time I also faced the problem. If there are parallel processes, the C/T time will be taken for the process which takes the maximum time. Of course it will be applicable when each of the parallel processes are independent.